Prime Minister David Cameron) outlined plans to seize passports from British militants and stop them returning from fighting overseas, while proposing landing bans on airlines that fail to comply with London's no-fly lists.

Some 500 radicalised Britons are estimated to be fighting in Iraq and Syria, both of which are facing a major offensive from the Islamic State militant group.

British media reports said the legislation, to be introduced in parliament this month, would block individuals from returning from Syria and Iraq to Britain for at least two years unless they comply with strict measures.